Fanning ore concentrator



March 3, 1959 R, v 'SPENCER 2,875,898

' FANNING ORE CONCENTRATOR Filed Sept. 13, 1954 United States Patent() FANNING ORE CONCENTRATOR `Robert V. Spencer, Jacksonville, Fla., assignor to James Hall Carpenter, Jacksonville, Fla.

Application September 13, 1954, Serial No. 455,631

' 1s claims. (c1. 209-458) This invention relates to ore concentrators and particularlyto a concentrator embodying a novel fan arrangement for vanning and fanning or spreading and for splitting the stratified stream issuing from the discharge end of a sluice.

A general object of this invention is to improve the concentrating of ores, and more particularly to provide means for spreading and stratifying a stream of granular or comminuted materials entrained in a stream of liquid.

A further object of this invention is to improve the accuracy of splitting of the ore constituents present in a stratified stream of ore particles, and to simplify the appropriate'adjustments to splitter members in concentrators.

A still further object of this invention is'to provide a pinched sluice type of wet ore concentrator or separator capableV of a moreV complete stratification of ore particles of respectively different sizes, shapes and specific gravities, operative to provide stratification and separation between particles of only slightly different respective specific gravities,-sizes and shapes.

Additional general-objects of this invention are to provide a sluice separator of greater simplicity capable of handling relatively large amounts of ore in 'a given time, with high separation or concentration efficiency, at a high pulp densityl and with minimum water requirements.

It is also an object of this invention to provide a simplified wet feed for a stratifyng sluice or trough, which feed will supply a sheet of pulp without surging and with a minimum of discontinuities of pulp density.

Sluice separators, sometimes called concentrators or classifiers, have been in use for a great many years, particularly in connection with the removal of heavy gold particles from relatively light,A valueless sand. Spiral concentrators, wet shaking tables and other types of wet gravity concentrators usually occupy considerable space, are of heavy construction and require relatively large quantities of accessory water or Wash water as an aid in the separation of minerals. The addition of wash water along a stream in which 'stratification is taking place is objectionable not only because of the equipment necessary for its 'supply but because any interference with the stream is likely to create turbulence in the stream which, in turn, may re-mix the particles which have become stratified or may cause `collection of dams built up of particles at the discontinuity in the ow, which dams change the shape of the fiow path disadvantageously.

A particular disadvantage of wet type sluice concen- 'trators which have heretofore been suggested lies in the sensitivity of adjustment of stream splitters, and in the necessity of testing the output components to discover the most appropriate setting ofl the splitters.

Among-the objects of the present invention, accord- 4the values in the lighter material strata.

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. 2 ingly, are the avoidance of the complexities of other gravity separators and the provision of a simple preconditioning arrangement, such as a simplestraight flow sluice of the type having converging sides, the preconditioner having a deep or high and narrow outlet orifice, together with stream vanning and fanning means, and with splitter means capable of ready adjustment, so. arranged that the effects of each of several permitted adjustments are clearly and directly seen, permitting the immediate recognition of the need for adjustment without laborious and time-consuming tests of output constituents and the accomplishment of adjustments to the proper setting without trying out several different settings and thereafter awaiting test results to determine the best of the several settings.

Certain types of ores, such as those containing titanium minerals, among others, are desirably concentrated by wet gravity concentration means prior to final separation steps performed withelectrostatic, magnetic or similar separating machines. The differences in specific gravity between constituents of such ores may be relatively slight and it is an object of this invention to provide means to stratify the constituents` with increased accuracy or completeness of stratification, that is, with a minimum of lighter materials in the strata of heavier materials and a minimum of heavier materials in the lighter materials strata.- Since lighter materials may be discarded, it is particularly irnportant to avoid the inclusion of substantial quantitiesA of It has also been found that titanium ore deposits in certain parts of the worldvaryfmarkedly within a single deposit as to richness. Thus, while ore delivered from the mine for concentration at one time may comprise only one or two percent heavy minerals, a few minutes later the ore delivered from the mine may have thirty percent heavy minerals. Such Variations must be compensated by adjustment of the stream ldividing means of the gravity concentrator to prevent excessive-losses in the tailings when the ore isV rich and to prevent excessive sand in .the concentrate output when the ore is less rich.

It is, accordingly,`a further object of this invention to provide a concentrator permitting ready visual inspection of the stratification of the stream being split and visual determination of the most advantageous splitter settings, together with provisions for rapid readjustment of splitter position to compensate for such variations in richness of ore as soon as the variations are lfound to occur.

The novel features which are believed to be characteristie of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in which:

Fig. l is a perspective view -of a wet ore concentrator in accord with this invention;

Figure 2 is a detail back view,vin perspective, of the discharge end and fan and splitter portions o f the concentrator; andV v Fig. 3 is a detail end view, in perspective, of the discharge end and fan and splitter portions of the concentrator. l

A concentrator according to this invention, as shown in Fig. 1,' comprises a vertical pulp supply pipe 1 through which the ore pulpis pumped, as by va centrifugal pump, into the lower or apexial end of a generally inverted triangular conduit chamber 2. Chamber 2 preferably is of constant thickness, which may be about two inches,

and increases in breadth from about two or three inches at the lower end or apex to about twenty inches at the upper end, and being about twenty-one inches high. The long upper edge at the front of the chamber 2 is formed to provide a lip 3 over which a sheet of pulp ows, while the other Vthree sides of the top of chamber 2 are enclosed with walls ,terminating sutiiciently above the level of the lip to prevent spilling'4 of the pulp except over the lip.v The upper end of the conduit 2 may be left open, or closed over as desired.

The sheet of pulp flowing or cascading over lip 3 falls preferably a very short distance and at a very low velocity vonto the relatively wide upper end of a downwardly inclined tlat bottom portion'4 of a trough or s luice, indicated generally at The sluice 5 may be ltertnecl a pinchedfsluice, in that its vupstanding side walls 61ans 7 Whih @fue thellcw 'offrlnsradlly ap- Pmacb each other ,er snves@ .t9 sive ",agnllr triangullar shape to the sluice; lfhe side wal-ls "6 and A7 format theinlower or forward `ends Aa tall ory high and'nar'row outletopening from which the pulp* issues in a tall 'and high stream. During its course down the sluice, the pulp lbecomes stratified, 'the heavier materials, that is, the materials of greater specific gravity, dropping in the stream and forming a lower strata, while the lighter materials of less Vspecilic gravity tend to remain in the upper portions of the stream and lform higher strata. It will `be understood that the stratification is not complete, in that the lower portions of the stream contain some percentage of lighter particles andthe intermediate and upper strata contain some yheavy particles. The usefulness of the concentrator herein disclosed, accordingly, will Abe primarily to provide from a granular or comminuted ore as mined, and which may comprise a small percentage of, for example, heavy minerals, a concentrate of relatively much higher heavy mineral percentage. ln connect'ion with certain specific oresas hereinafter explained it'has been `found economicand desirable to pass the pulp of ore from the mine through a concentrator according `to the invention and .to collect a concentrate portion, a middlings portion kand a tailings portion from the stream and then to pass the middlings again through the same concentrator, or throughanother such concentrator. The middlingsmay, for,example, be mixed vin with the raw f eedfor the same unit, or middlings from two units may 'be passed together into a third unit, and many other variations of the vflow plan for re-concentration of middlings will be obvious to those skilled in the art. The tailings mayjbe similarly recirculated in some instances ormaybe'discarded. rlfo permit the separate collection o f, thef three strata as suggested, two splittersin the form of shortfsplitter .bars ormembers are provided for the concentrator shown, although it will be understood that ifonly one splitof the vstreaminto two portions is desired, only one splitter will be required, and, if more than vvthree portions are desired,.additional splitters may be employed.

As seen in Fig. l, splitters or splitter bars 9 and l0 are arranged to extend outwardly from the front face 11 of a vanning and fanning plate member r1,2, which .is preferablydlat as shown. Each splitter comprises essentially a wedge-shaped member having Va relatively sharp upper cutting edge, such as edge 13.and divergent sides, vsuch as sides 14.and` 1 5. The splitter members shown are formed of sheet metal bent to'provide the sharp upper cutting `edge 13, downwardly and outwardly inclined sides "14 and 15, and a base portion 16, the base portion of each splitter being aixed by welding or by other suitable means to the end of a respective o ne of supporting arms f17 and'18. The splitters 9 and1 0 are held firmly against the surface 11 fplate 1 2'by the supporting arms v17 and 1 8,

^ ,and ,thepath /of the stream across rthe Vplate surface is -indicated in broken 'lines. V As the stream courses down Vthe sluice,v Ythe stream rises gradually higher on the walls 6 and 7, and the height of the stream is generally indicated by broken line 19 along wall 6. The stream issues from outlet 8 in the shape outlined between lines 20 and 21 and is intercepted by or impinges upon the plate surface 11 at approximately the area below the break indicated at 22, thereafter fanning out across the plate below and beyond the area of impingement, as indicated by the .upward spread of line 23. The stream from the outlet orifice S preferably passes freely through the air for about two to four inches before impinging on the plate surface, and the plate surface should be at an average angle of approximately 15 degrees to the direction of the stream as the stream meets th'e'plate, greater angles than about 25 degrees causing undesirably great turbulence on contact and less angles than about l0 degrees yielding less vanning and fanning eject. Since lower parts of the streaml mayn be moving more nearly vertically downwardly than upper parts upon impingement, there is no one angle of impingement, and the impingement angle herein given is therefore as closely as possible approximated as the average angle taking all parts of the impinging stream. A specific setting of the plate position which has proved appropriate, for example, in the specific concentration of ore from Gambia as hereinafter reported comprised a tilting of the plate at an angle of 28 degrees from a line through the plate which line was constructed as perpendicular to the plane of the Abottom 4 of the sluice, and the plate was arranged to form an angle of 5 degrees with the center line of the bottom 4 of Vthe sluice, as measured in the plane of the bottom. i

The fanned portion of the stream beyond and below the area of impingement of the streamen the plate is split by splitters -9`and 10 to form three output streams, which may be termed a heavies o r concentrate stream 24, a middlings stream 25 and a tailings Vstream 26. The tailings are oftendiscarded but maybe again furnished to aconcentrator if desired. The middlings are usually directed to pass through a concentrator again, while the heavies 24 may, for example, be collected, dried and passed through magnetic or electrostatic separating machines, all as dictated by the type and constitution of the particular ore and the desired end results. The heavies 24 and rniddlings 25 are collected -in any desired type of launders as is conventional in the art, such launders being omitted from the drawing for simplicity. The tailings 26 vmay be collected or discarded as required.

The lip -3 Qshould -'be as nearlyV as Vpossible horizontal from end to end, and the bottom 4 of the sluice should be horizontal from side to side'l and inclined downwardly from itswide uppere'nd, at'the lip, toward the discharge end at outlet Sat an angle of between l5 and 25`d`eg'rees tothe horizontal. The minimum angle of inclination at which build-up of ore particles in the sluice 'does not occur is preferred, and for a rate of flow of 1.5 tons (dry weight) of ore per hour, and for a pulp of 60% by weight of solids entrained in 40% by weight of water, or 60% pulp density, a slope of 19 degrees has proved satisfactory. Greater pulp density normally requires greater slope, and less density, less slope. The angle of inclination is readily adjusted by means of a turnbuckle 27 which supportsthe sluice from conduit chamber 2. Chamber2 is conveniently attached to rigid Vsupporting posts 28.which,may if desired compriseleveling means, not shown, lto,level lip v3 and sluice bottom 4. The upper end of sluice ,Sis

connected through pivot pins 29 to the upper end of chamber member 2 permitting adjustment of inclination.

Fig. 2 kshows the back of fanning plate 12 which has apivotfpost 30 attached thereto. Post 3.0 carries arms 17'and l18. pivotallythereon, and thearms extend ,to Vand under the preferably arcuate lower and forward edge 31 of the plate member. A bolt 32 is threaded through each arm in a position such that screwing in the bolt will cause thearm to be urged or forced away from Vthe back Aof plate 12 and will cause the arm to be locked 'in position.

Release is accomplishedfor adjustment vof the armA by unscrewing the bolt a few turns. j

4The plate has welded thereto a small angle member 33 and the upper portion of the angle member is bolted, by bolt 34, to a second angle member 35, having an adjusting slot through which bolt 34 passes.'V Angle member 35, in turn, is bolted to a generally upright arm 36, vertically slotted for bolt 37, and which is pivotally adjustably connected by bolt 38 to an arm 39 aixed to the outer surface of sluice wall 6.

The universally adjustable mounting arrangement comprising arm 39, angle 35 and angle 33, together with the several bolts, is further seen in the end view of Fig.` 3. As seen in Fig. 3, angle member 35 may be adjusted vertically alongarm 36, by loosening bolt 37 and moving the bolt along the slot of arm 36.l Arm 36 may be pivotally adjusted von bolt 38 and the bolts 37 and 34 afford means to adjust the angle of the plate. After any adjustments, any of bolts 34, 3.7 and 38 which have been loosened are, ofcourse, tightened to lock the plate in its adjusted position. The plate, accordingly, may be adjusted as to angles of inclination, as well as up and down, back and forth and in and out.

A spring finger 40 isaixed to the inner surface of each of arms 17 and 18 and each is arranged to bear against the back surface of plate 12u/ith suicient force to oppose and normally to prevent unintended changes in position of its respective arm. The arms are locked, however, by tightening the appropriate bolt 32 which engagesflinger 40 and .increases the locking force on the arm. The

.effect ofthe respective ngers 40 and bolts 32 is also to draw the splitters 9 and lrespectively rigidly andrmly against the ,operative face of plate 12.

The whole inner surface of the sluice, including bottom 4 and side walls 6 and 7,4 is preferably smoothly faced with neoprene or rubber, which is resistant to wear, and the face 11 of fanning plate 12 is preferably covered with a smooth flat s heet of white rubber or neoprene, made vwhite to permit a ready observation of the minerals concertain purposes it may be found desirable toV provide an appreciable curvature. It will be apparent that the arcuate shape of the lower forward edge of the plate is convenient for the type of mounting of the splitters herein shown but that the lower edge shape does not in any way affect the concentration or separation function, it being necessary only that the plate surface extend beyond and :below the area of impingement to permit the fanning and `vannng functions of the plate.

As a specific example of operation of a fanning concentrator of the type herein disclosed, the concentrator w-as used to concentrate an ore mined from dunes adjacent the seashore approximately fifteen miles south of the city of Bathurst in Gambia, British West Africa, the ore being a comminuted or granular ore comprising approximately 48% by vweight of heavy mineral values, primarily ilmenite, Zircon and rutile, with minor amounts of garnet, staurolite and other accessory minerals of slightly less specic gravity than the first three mentioned, but slightly greater specific gravity than the balance of 52%V quartz sand. VIn one passthrough a concentrator as shown, utilizingtwo splitters, the dimensions of the concentrator being substantially those heretofore suggested as exemplary, the following tables indicate the results obtained ,y as measured by the percentage dry weight of the.desired 'heavy minerals contained inthe concentrates, middlings f and tailings, respectively.

`6 'Instr No. 1

Gambia ore-as mined 63.0% pulp densityV v Y Calculated head feed 48.16% heavy minerals The above results were obtained by taking timed grab samples and as the percentage of heavy minerals in the new feed vary throughout the bulk the percentage of heavy minerals in the resulting products will vary accordingly. For this reason the tailings for the Test No. l do not correspond exactly with the feed tov Test No. 2 insofar as heavy mineral content is concerned.

While the specific embodiment of this solution shown and described herein comprises, as a pre-conditioner of the pulp, a pinchedY sluice, it is believed that the most effective stratification and separation of the heavy minerals from the sand particles occurs on the plate surface 11. Stratification also occurs within the deep and-narrow stream between the outlet orifice 8.and the point or area of impingement of Vthe stream on the plateJlAccordingly, this `invention may be practised withV a pr'econditioning arrangement other than a pinched sluice, and for some applications commercially practical concentrations may be performed even 'though the pulp issues from a deep and narrow orifice without any appreciable preconditioning or stratification of the stream before it reaches the orifice.

While only certain preferred embodiments of this invention have been shownand described by way of illustration,many modifications will occur to those skilled in the art and it is, therefore, desired that it be understood that it is intended in the appended claims to cover all such modifications as fall .within the true spirit and scope of this invention.

What is claimed as new and what it is desired to secure by Letters Patent of the United States is: n

l. In a Wet commnuted ore concentrator, sluice means to provide a thin, deep stream'of liquid pulp of generally rectangular cross sectional shape issuing in a predetermined direction from said means with a substantial component of velocity in a horizontal direction, said stream being at least partially stratied to carry a lower strata of heavier ore particles and an upper strata of lighter particles, a plate having a at surface positioned to intersect said stream at an area of` said plate surface `spaced from said means, said plate surface being disposed at an average angle of less than twenty degrees to `the ldirection of said issuing stream'at said area, and being oriented to dellect said Astream to one side, said plate sur-face extendingI beyond and below said area, and splitter means positioned against said plate surface and extendiiig'gererallyi perpendicularly outwardly therefrom through the spread path of said stream beyond and below said'area of said stream-intersectecl surfaeplate,

2. In a Wet. gravity type comminuted ore concentrator, a downwardly .inclined trough having side walls gradually `converging'and having end portions dening the sides of a deep narrow outlet for said trough, a white siirfaced plaie 'disposed opposite' and 'beyond said outlet and having'j'portion of its said surface positioned to be impingned'by a liquid strearnissuing `from said outlet, said portioiibeing' substantially dat and slanted at a slight ausl@ to. the direction @f motion of. said issuing stream at said portion, whereby said impinging stream fans out against the surface of Ysaid plate generally below and beyon'd'said'"portion,` splitter"means extending outwardly fromfthe surface off said' plate into said farmed out portion of said stream, and means to adjust the position of said v splitter means in directions across said fanned out stream. A' n i 3. In a wet vgravity comminuted ore concentrator, in combination with means to supply a deep and narrow pulp lStream into the air with a substantial component of horizontal velocity, a vanning plate having a surface positioned for impingementby saidv stream and making an acute angle with Vthe side of said stream, as measu'rled in a plane perpendicular to said side and extendin in the direction of stream motion at impingement, said angle being lsufficiently small i to' create little turbulence upon ,impingcmen said surface extending below and b eyond'tlieareal of impingement and being inclined to the vertical inadirection to retain said stream in fanned out shape thereon, and splitters in said farmed out stream and lspaced below and beyond said area of impingement,

4. A' wet gravityy comminuted' ore concentrator comprising meansto deliver a stream of pulp in a predetermined direction and with'a substantial component of horizontal velocity, said stream having a cross-sectional shape which is deep 'and narrow, a vanning plate having asurfa'ce area disposed toV be impinged by said stream ata small angle to said stream direction, said plate ex- Aitending*generally below and beyond said area in a direction tc'cause4 said stream 'as redirected by said irnpingemcnt on 'said area to fan out over said plate beyond and below said areafafnd meansfor dividing for collec- -ti n desired fractions of said stream, said means including V,stream splitters disposed in said fannedout stream adjustable'nieans'connecting said splitters to said plate. 5.`"In'combinat ion, a vertical pulp supply conduit com- V'prising`a'generally'triangular chamber of uniform thickness having an inlet opening into the narrow lower end r thereof and having a wide upper outlet bordered on one long side'by a lip'adapted to supply' a thin sheet of pulp thereover, a' generally triangular trough having a flat downwardly'inclined bottom, wide at the top and disposed at the top underiand adjaccntsaid lip' to receive said sheet of pulpiflowin'g over said lip, said trough having upstanding side walls confining the stream of pulp on said bottoniaiid lgradually :converging toward the lower end of said ktrough and'forming at said lower end a narrow highfoutletopening, a fan'plate having a preferabiy flat frontfce" 'and aback portion, universally adjustable mounting means connecting said plate at said back portion to an exterior portion of 'said trough, said means being adapted and arrangcd'tosupport said plate with said front face thereof in position to be impinged upon by the stream of pulpissuingfroin said outlet, a mounting arm pivotaliy attachedito Isaid back'portion on a'pivot axis spaced upwardly of the lower 'edg'e of said fari plate, said arm eX- tending to said edge` and under said edge, a splitter mem- .bei' attached to said arm anddisposed against said front lpositionfhis'aid front face by 8 swinging of said arm on said pivot axis, and relea ble forcei'means elgagirigl between said'bacli'poiftiori af' Y arm operative to urge sai 'afm and bck'JOi therebyloforce said'sp y I f said.u front vface- 4and releasably Ytoflofck said, splitteifmemf'- berin'it's ladjusted'posi n. v

' 6. In" a'pin'cled Ysluice'comminuated ore concentrator having van outlet oricc 'for delivering with a "substantial horizontal dvelocity ncomponent deep narrowl stream with'p'articles stratied in accord with'ther, ,cie tive specic gravities entrained therein, a fann'ing'rnembei havinga surfaceportion disposed in spaced relation to said outlet orifice and in position to be impingedf'upon by said liquid stream 'atanaverage"imiingomentaugl as measured'between thefside loffsaid 'st'rea and said" surface portion of not moretlian" substa whereby turbulence of said stra'rrfupon unpl4 minimized, vsaid surface V`portion lieing'r'icline'dffr im 2the vertical by an angle greater vthan saidavr g ande", the surface of said plate extending belowv andbeyondsaJd pingedY portion thereof and being adapted and arranged 'to van and fan said stream, and splitter'means positioned below and beyond said Virnpinged portion 'to split'sald tanned stream into at least two streams having respectively different concentrations of patricles of diierer'it specific gravities. i l A 7. In a comminuted material concentrator, downwardly inclined preliminary stratification planar surface means, means to deliver a substantially constant flow of sai'dfmaterial to the upper end of said surface, 'means 'to 'restrict the material between lateral bounds on said surfac'ei'said last means being arranged to ,constrict'iand direct said materialinto a narrow outlet path at lower-'end of said surface, the inclination of said surface being sulicient to ycause said material to dow there'oveunderfthe force of gravity from said upper to said 'lower end,aI tanning plate positioned to intercept the comminuted material in said outlet path following the issuancetherof from ksaid lower end of said surface, said plate beingl positioned at an acute angle of less than 25 degrees to theV direction of motion of said stream at the area of interceptitni thereof and said plate extending downwardly andbeyond said area of interception thereby to fan said material overy arportion of said plate, and splitter means at saidn portion disposed to extend outwardly'from the surface of said'plate.'A

8. A pinched sluice wet'y ore concentrator comprising an upstanding generally inverted triangular hollow conduit with a relatively small apexial inlet openingl atithe bottom 'to receive a flow of ore pulp underipressure and a'relatively much larger delivery opening at the top, saiddelivery opening having a length at leastapproxlirnatlyl live times its ywidth and Ahaving a horizontal delivery lip along a long side thereof, a downwardly inclined troughihaving a bottom positioned with its upper vend parallel-ifo, below and immediately adjacent to said lip and having side walls converging from the upper to the lower end-to 'form an outlet orifice, and splitter means for the stream issuing from said orifice. Y i' Y l '9. In a wet comminuted ore concentrator, an upstanding generally inverted triangular hollow conduit 4with Va relatively small apexial inlet opening at the bottom to re ceive a ow of ore pulp under pressure and a relatively much larger delivery opening at the top, said Ydelivery opening having a length at least approximately five times its width and having a horizontal delivery lip along a long side thereof, and stratifying sluice means having an upper end disposed under said lip to receive the ore pulp owing thereover. v i v u 10. The method of separating comminuted ore particles of dilering respective specific gravities which comprises the steps of forming a pulp comprising a liquid with said comminuted ore particles suspended therein, flowing said pulp down a Vflat downwardly inclined vsurface',gradually increasingly restricting the stream widfth'of said Ypulp along its direction of flow 'on'said surface i strcted width stream to issue freely over a lower edge of said surface, intercepting said freely owing pulp stream with a planar surface so positioned and canted as to locate the area of impingement of said stream thereon spacedly beyond and below said lower edge and as to form an angle of interception of said stream of less than 25 degrees, and splitting the stream fanned on said planar surface.

1l. The method of concentrating comminuted ore and the like wherein a deep and narrow stream of ore or the like pulp with a substantial component of horizontal velocity is directed against a vanning plate which extends at a sufficiently acute angle to the direction of the stream just prior to impingement, as measured in a horizontal plane, to create little turbulence on impingement and which extends below and lbeyond the area of impingement, and said fanned out stream is split into a-plurality of separate streams.

l2. In an ore concentraton a plate having an arcuate edge, means to impinge moving ore particles against a front surface of said plate to fan toward said arcuate edge, a splitter member having a splitting edge directed into the fanned path of said particles and having an end of said member in contact with said surface, a pivot on the back of said plate equidistant from spaced points of said arcuate edge, an arm structure supported on said pivot and extending to and around said edge and having a swngable end aixed to said splitter member, said arm structure comprising force means engageable with the back of said plate urging said arm structure away from said back surface thereby to urge said splitter member toward said front surface.

l3. In an ore concentrator, a plate having an arcuate edge, means to impinge ore particles against a front surface of said plate to fan toward said arcuate edge, a splitter member having a splitting edge directed into the fanned path of said particles and having an end of said member in contact with said surface, a pivot on the back of said plate equidistant from spaced points of said arcuate edge, an arm structure supported on said pivot and extending to and around said edge and having a swingable end aiixed to said splitter member, said arm structure' comprising force means engageable with the back of said plate urging said arm structure away from said back surface thereby to urge said splitter member toward said front surface, said force means comprising manually operable means for adjusting the amount of urging force on said arm structure.

References Cited in the le of this patent UNITED STATES PATENTS 977,956 Langerfeld Dec. 6, 1910 1,828,760 Blatch a Oct. 27, 1931 2,644,583 Cannon Iuly 7, 1953 

